Flatten photo group

[gcellison]

I am enhancing photographic images for a website. This includes the typical processes of lightening, darkening, modifying saturation, etc. Some images also include manipulations like clone/magic erase and photo heal. I’m very please with the results, but I know that these processes are heavy for file size and processing.

Some of you are undoubtedly familiar with the tool to “flatten photo group”. My understanding is that it combines all of the modifications, making a much lighter image. Unfortunately, the tool is hardly mentioned in the manuals. In both the P&GD and WDP manuals: “Flatten photo group … Converts a photo group to a single bitmap.” is the only mention of the tool, with no elaboration whatsoever. In the Xara website, in the article on “WHAT IS A PHOTO GROUP?”, the only mention is “You can 'flatten' a Photo Group to become a normal JPEG by selecting the Photo Group and the menu Utilities -> Optimize Photo...” This is at least nominally not the same tool as “flatten photo group”, although it might accomplish the same thing.

I have experimented with the tool. My image (516 x 152 px) was modified for brightness, contrast, shadows brightness, and saturation. Additionally, the specific color range in a region of the photo was enhanced to boost the saturation more. The modified image exports as a jpeg at 74.2Kb using 85% quality. When I use the flatten photo group tool, the same image exports at 15.0Kb.

To the naked eye, there appears to be little difference, even on high zoom. Resemble.js image analysis and comparison, however, shows a 72.72% difference between the two… but ignoring color variations, that the two are essentially identical.

So, my question for anyone who has used or considered using the flatten photo group tool: what is your advice? Is it better to leave the photo group in the project (for example, in case of later modifications) or do you prefer to lighten the project by flattening the groups? And of course, what is behind that preference?

Any comments are appreciated.

[gwpriester]

Yes, I use this all the time in Designer Pro X. Xara has many "Live effects". This means that when you edit a photo as you have detailed, the changes can be edited or deleted. Also even though you might only be using a small area of a photo, the entire photo is still there. When you Flatten the Photo Group Xara adds all the changes to a new photo. The files size is smaller, but you cannot undo the previous edits.

I use the Photo Tool > Select Colors to Edit to make colored backgrounds transparent. But this leaves a faint outline in the visible areas. When I apply Flatten Photo Group, this disappears.

[gcellison]

Thanks very much for your advice, gwpriester.

Sometimes I decide to change an image after my first design. It usually doesn't entail enhancements, but more likely resizing or changing the cropping. It appears that flattening photo groups is a destructive process.

I believe I will keep the modified images in separate .xar files and paste the flattened images into the website project. That way I will still have access if I want to change things later.

Thanks again,
Greg

[gwpriester]

That's a very good idea.

[Egg Bramhill]

So, my question for anyone who has used or considered using the flatten photo group tool: what is your advice? Is it better to leave the photo group in the project (for example, in case of later modifications) or do you prefer to lighten the project by flattening the groups? And of course, what is behind that preference?

Greg, my general choice on this matter would not be to optomize images. I would only do so if my xar/web file became slow & cumbersome to load. {Perhaps time to split your site into subsites?}. Optomise(Flatten?) is destructive. When you publish your website the image is optimised for browser display, but the image remains large-format, clipped, filtered etc. within Xara for future amendment.

[gcellison]

Thanks, Egg. I agree. I've never optimized in the past until I was ready to export the final version for upload to the hosting server. Even then, I kept the pre-optimized project file separate in case of later modifications. Now that I understand more accurately that the "flatten photo group" is essentially optimization, i.e., destructive, I will keep the permanent version of my modified images pre-optimized.